Résumé
The Sabkha of El Breij has yielded the oldest marine Eocene vertebrate fauna from the Sahara Desert in southwestern Morocco. Fossils come from three distinct layers in the Samlat Formation sequence. Selachian teeth are abundant at all levels. The selachian assemblage in the lower level indicates a Lutetian-early Bartonian age. The selachian taxa of the two upper levels indicates an upper Bartonian age. The lower horizon yields abundant fossil remains of two protocetids, the very large Pappocetus lugardi and a smaller medium-sized protocetid. Protocetids are associated with rare remains of bony fishes, turtles, crocodyliforms, and a paleophiid snake (cf. Palaeophis moghrebianus). The two upper fossiliferous levels (Bartonian) are about 20 m above the lower level. They yielded remains of three genera of Basilosauridae: Chrysocetus, Platyosphys, and Eocetus, associated with abundant chondrichthyans, and remains of bony fish, turtles, crocodyliforms, and seabirds. Turtles are represented by a pleurodire species of the subtribe Stereogenyina, probably Cordichelys antiqua, and another pleurodire form remains to be determined. The crocodile vertebrae show that it is a Eusuchian, and the shape of the quadrate suggests a gavialoid. The two specimens of pseudotoothed birds (Odontopterygiformes, Pelagornithidae) are tentatively assigned to the genus Pelagornis, which together with Pelagornis from the Bartonian of Gueran constitutes one of the earliest records of this genus.